New data from the Cocoa Supplement and Multivitamin Outcomes Study (COSMOS) suggest that a daily multivitamin may help protect the aging brain. However, at least one expert has concerns about the study's methodology and, as a result, the interpretation of its findings.
The meta-analysis of three separate cognition studies provides "strong and consistent evidence that taking a daily multivitamin, containing more than 20 essential micronutrients, can help prevent memory loss and slow down cognitive aging," study investigator Chirag Vyas, MBBS, MPH, with Massachusetts General Hospital and Harvard Medical School, Boston, told Medscape Medical News.
"We are not now recommending multivitamin use, but the evidence is compelling that supports the promise of multivitamins to help prevent cognitive decline," Vyas said.
The new data, from the cognitive substudies of COSMOS, were published online on January 18 in the American Journal of Clinical Nutrition.
Clinically Meaningful Benefit?
To recap, COSMOS was a 2 x 2 factorial trial of coca extract (500 mg/d flavanols) and/or a daily commercial multivitamin-mineral (MVM) supplement for cardiovascular disease and cancer prevention among more than 21,000 US adults aged 60 years or older.
Neither the cocoa extract nor the MVM supplement had a significant impact on cancer or cardiovascular disease events.
COMOS-Mind was a substudy of 2262 participants aged 65 or older without dementia who completed telephone-based cognitive assessments at baseline and annually for 3 years.
As previously reported by Medscape Medical News, in COSMOS-Mind, there was no cognitive benefit of daily cocoa extract, but daily MVM supplementation was associated with improved global cognition, episodic memory, and executive function. However, the difference in global cognitive function between MVM and placebo was small, with a mean 0.07-point improvement on the z-score at 3 years.
COSMOS-Web was a substudy of 3562 original participants who were evaluated annually for 3 years using an internet-based battery of neuropsychological tests.
In this analysis, those taking the MVM supplement performed better on a test for immediate memory recall (remembering a list of 20 words); they were able to remember an additional 0.71 word on average compared with 0.44 word in the placebo group. However, they did not improve on tests of memory retention, executive function, or novel object recognition.
The new data are from COSMOS-Clinic, an analysis of 573 participants who completed in-person cognitive assessments.
COSMOS-Clinic showed a modest benefit of MVM, compared with placebo, on global cognition over 2 years (mean difference, 0.06 SD units [SU]), with a significantly more favorable change in episodic memory (mean difference, 0.12 SU) but not in executive function/attention (mean difference, 0.04 SU), the researchers reported.
They also conducted a meta-analysis based on the three separate cognitive substudies, with 5200 nonoverlapping COSMOS participants.
The results showed "clear evidence" of MVM benefits on global cognition (mean difference, 0.07 SU; P = .0009) and episodic memory (mean difference, 0.06 SU; P =.0007), they reported, with the magnitude of effect on global cognition equivalent to reducing cognitive aging by 2 years.
In a statement, JoAnn Manson, MD, DrPH, chief of the Division of Preventive Medicine at Brigham and Women's Hospital, who led the overall COSMOS trial, said that "the finding that a daily multivitamin improved memory and slowed cognitive aging in three separate placebo-controlled studies in COSMOS is exciting and further supports the promise of multivitamins as a safe, accessible, and affordable approach to protecting cognitive health in older adults."
Not a Meta-analysis?
In an interview with Medscape Medical News, Christopher Labos, MD CM, MSc, a cardiologist and epidemiologist based in Montreal, Canada, who wasn't involved in COSMOS, cautioned that the evidence to date on multivitamins for memory and brain health are "not all that impressive."
Labos is a columnist for Medscape and previously has written about the COSMOS trial.
He said it is important to note that this "meta-analysis of COSMOS data, strictly speaking, is not a meta-analysis" because the patients were all from the original COSMOS study without including any additional patients, "so you don't have any more data than what you started with.
"The fact that the results are consistent with the original trial is not surprising. In fact, it would be concerning if they were not consistent because they're the same population. They were just assessed differently — by phone, online, or in person," Labos explained.
"It is hard to tell what the benefit with multivitamins actually means in terms of hard clinical endpoints that matter to patients. Scoring a little bit better on a standardized test — I guess that's a good thing, but does that mean you're less likely to get dementia? I'm not sure we're there yet," he told Medscape Medical News.
The bottom line, said Labos, is that "at this point, the evidence does not support recommending multivitamins purely for brain health. There is also a cost and potential downside associated with their use."
Also weighing in on the new analyses from COSMOS, Claire Sexton, DPhil, Alzheimer's Association senior director of scientific programs and outreach, said while there are now "positive, large-scale, long-term studies that show that multivitamin-mineral supplementation for older adults may slow cognitive aging, the Alzheimer's Association is not ready to recommend widespread use of a multivitamin supplement to reduce risk of cognitive decline in older adults.
"Independent confirmatory studies are needed in larger, more diverse, and representative study populations. COSMOS-Clinic, for example, had less than 2% non-White in the multivitamin group and 5% non-White in the placebo group. It is critical that future treatments and preventions are effective in all populations," Sexton told Medscape Medical News.
She noted that multivitamin supplements are "generally easy to find and relatively affordable. With confirmation, these promising findings have the potential to significantly impact public health — improving brain health, lowering healthcare costs, reducing caregiver burden — especially among older adults."
The Alzheimer's Association, Sexton told Medscape, "envisions a future where there are multiple treatments available that address the disease in multiple ways — like heart disease and cancer — and that can be combined into powerful combination therapies, in conjunction with brain-healthy guidelines for lifestyle, like diet and physical activity."
The Alzheimer's Association is leading a 2-year clinical trial known as US POINTER to evaluate whether lifestyle interventions that target multiple risk factors can protect cognition in older adults at increased risk for cognitive decline.
COSMOS-Clinic and the cognition studies in the meta-analysis were supported by investigator-initiated grants from Mars Edge, a segment of Mars Inc., and the National Institutes of Health. Multivitamin and placebo tablets and packaging were donated by Pfizer, Inc Consumer Healthcare (now Haleon). Disclosures for the COSMOS investigators are available with the original article. Labos and Sexton have no relevant disclosures.
Am J Clin Nutr. Published online January 18, 2024.